U.S. patent application number 16/614966 was filed with the patent office on 2020-06-11 for triboelectric sensor.
The applicant listed for this patent is SABIC Global Technologies B.V.. Invention is credited to Ramzi Salem AL-MAGHATHUWI, Abdulaziz Hamad M. ALDUBAYAN, Fahad ALSALEM, Jesus Alfonso Caraveo FRESCAS, Pradipta K. NAYAK.
Application Number | 20200183511 16/614966 |
Document ID | / |
Family ID | 59014673 |
Filed Date | 2020-06-11 |
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United States Patent
Application |
20200183511 |
Kind Code |
A1 |
FRESCAS; Jesus Alfonso Caraveo ;
et al. |
June 11, 2020 |
TRIBOELECTRIC SENSOR
Abstract
A triboelectric-based sensor can be used to receive touch-based
input from a user and control electronic devices. The
triboelectric-based sensor can be constructed with a thin film
layer underneath a triboelectric later. The thin film layer may
include a high resistance portion and a low resistance portion. The
low resistance portion can be used to couple the triboelectric
layer to the high resistance portion. The high resistance portion
can have a serpentine shape and have dimensions and a sheet
resistance designed to function as a thin film resistor for the
triboelectric-based sensor.
Inventors: |
FRESCAS; Jesus Alfonso Caraveo;
(Thuwal, SA) ; ALDUBAYAN; Abdulaziz Hamad M.;
(Thuwal, SA) ; NAYAK; Pradipta K.; (Thuwal,
SA) ; AL-MAGHATHUWI; Ramzi Salem; (Thuwal, SA)
; ALSALEM; Fahad; (Thuwal, SA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SABIC Global Technologies B.V. |
Bergen op Zoom |
|
NL |
|
|
Family ID: |
59014673 |
Appl. No.: |
16/614966 |
Filed: |
May 19, 2017 |
PCT Filed: |
May 19, 2017 |
PCT NO: |
PCT/IB2017/052967 |
371 Date: |
November 19, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G06F 3/041 20130101;
H03K 17/96 20130101; H02N 1/04 20130101 |
International
Class: |
G06F 3/041 20060101
G06F003/041; H03K 17/96 20060101 H03K017/96; H02N 1/04 20060101
H02N001/04 |
Claims
1. An apparatus, comprising: a triboelectric material; and a thin
film layer coupled to the triboelectric material, wherein the thin
film layer comprises an electrode portion coupled to the
triboelectric material and a resistive portion coupled to the
electrode portion, wherein the resistive portion has a higher
resistivity than the electrode portion, and wherein the thin film
layer comprises a transparent conducting oxide.
2. The apparatus of claim 1, wherein the transparent conducting
oxide comprises at least one of tin-doped indium oxide (ITO),
aluminum-doped zinc oxide (AZO), gallium-doped zinc oxide (GZO),
tin dioxide (SnO.sub.2), and fluorine-dope tin oxide (FTO).
3. The apparatus of claim 1, wherein the triboelectric material is
above and in electrical contact with the electrode portion of thin
film layer.
4. The apparatus of claim 1, wherein a portion of the triboelectric
material and a corresponding portion of the electrode portion form
a triboelectric-based sensor, and wherein a portion of the
resistive portion comprises a serpentine shape extending laterally
from the triboelectric-based sensor to form a thin film
resistor.
5. The apparatus of claim 4, further comprising a flexible
substrate, wherein the triboelectric-based sensor and the thin film
resistor are formed on the flexible substrate.
6. The apparatus of claim 5, wherein the flexible substrate is
transparent. The apparatus of claim 1, wherein the electrode
portion and the resistive portion comprise the same material, and
wherein the resistive portion of the thin film material comprises a
higher oxygen content than the electrode portion.
8. The apparatus of claim 1, further comprising a protective film
around the resistive portion of the thin film layer, wherein the
protective film comprises the triboelectric material.
9. The apparatus of claim 1, wherein the triboelectric material
comprises at least one of polyvinylidene fluoride (PVDF), a
copolymer of PVDF, polydimethylsiloxane (PDMS),
poly(methylmethacrylate) (PMMA), polytetrafluoroethylene, polymer
foam,
poly(methylmethacrylate)-co-poly(1H-1H-perfluorooctylmethacrylate),
poly-xylylene polymer, a fluorinated polymer, and an
electronegative polymer.
10. A method for manufacturing a triboelectric sensor device,
comprising: forming a first thin film layer comprising a
transparent conducting oxide and comprising an electrode portion
and a resistive portion, wherein the resistive portion has a higher
resistivity than the electrode portion; and forming a triboelectric
thin film layer above the first thin film layer and in contact with
the electrode portion of the first thin film layer, wherein at
least a portion of the triboelectric thin film layer is coupled to
at least a portion of the electrode portion to form a
triboelectric-based sensor, and wherein the triboelectric-based
sensor is coupled to at least a portion of the resistive portion
that forms a thin film resistor.
11. The method of claim 10, wherein the step of forming the first
thin film layer comprises: forming a conductive thin film material
in a first layer on a substrate, wherein the conductive thin film
material forms the electrode portion; and forming a resistive thin
film material having a higher resistance than the conductive thin
film, wherein the resistive thin film is in the first layer and
forms the resistive portion.
12. The method of claim 10, wherein the step of forming the
conductive thin film material comprises forming the conductive thin
film material by a lift-off process, the lift-off process
comprising: depositing a photoresist layer; patterning the
photoresist layer with a pattern corresponding to the electrode
portion; depositing the conductive thin film material; and removing
the photoresist layer to lift off portions of the conductive thin
film material not in the electrode portion.
13. The method of claim 10, wherein the step of forming the
resistive thin film material comprises incorporating oxygen into
the resistive thin film material to obtain the higher
resistance.
14. The method of claim 13, wherein the step of forming the
resistive thin film material comprises depositing the same material
as the conductive thin film material before incorporating oxygen
into the resistive thin film material.
15. The method of claim 10, wherein the step of forming the first
thin film layer comprises forming at least a portion of the
electrode portion or the resistive portion from at least one of
tin-doped indium oxide (ITO), aluminum-doped zinc oxide (AZO),
gallium-doped zinc oxide (GZO), tin dioxide (SnO.sub.2), and
fluorine-dope tin oxide (FTO).
16. The method of claim 10, wherein the step of forming the
triboelectric thin film layer comprises forming at least one of
PVDF, a copolymer of PVDF, PDMS, PMMA, tetrafluoroethylene, polymer
foam, poly(methylmethacrylate)-co-poly(1H-1H-perfluorooctyl
methacrylate), poly-xylylene polymer, a fluorinated polymer, and an
electronegative polymer.
17. An electronic device, comprising: a triboelectric-based sensor;
and an integrated circuit coupled to the triboelectric-based sensor
and configured to read-out a user input to the triboelectric-based
sensor, wherein the triboelectric-based sensor comprises: a
triboelectric material; and a thin film layer coupled to the
triboelectric material, wherein the thin film layer comprises an
electrode portion coupled to the triboelectric material and a
resistive portion coupled to the electrode portion, wherein the
resistive portion has a higher resistivity than the electrode
portion, and wherein the thin film layer comprises a transparent
conducting oxide.
18. The electronic device of claim 17, further comprising a
flexible substrate, wherein the triboelectric-based sensor is
formed on the flexible substrate, wherein the flexible substrate is
transparent.
19. The electronic device of claim 17, wherein the resistive
portion of the thin film material comprises a higher oxygen content
than the electrode portion.
20. The electronic device of claim 17, wherein a portion of the
resistive portion comprises a serpentine shape extending laterally
from the triboelectric-based sensor to form a thin film resistor.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] None.
FIELD OF THE DISCLOSURE
[0002] The instant disclosure relates to user input devices. More
specifically, this disclosure relates to user input devices based
on triboelectric sensors.
BACKGROUND
[0003] Electronic devices, particularly consumer electronics, must
interact with users of the devices by means for receiving input
from the user and means for providing output to the user. Classical
forms of input include keyboard and mouse devices, but also include
newer touch screen devices. However, these traditional techniques,
although well suited for particular applications, leave much to be
desired in low-cost, low power, and/or small-size form factors.
That is, keyboards and mice are fairly large devices that occupy a
large amount of space. In return, they offer the ability to handle
fairly complex inputs. Touch screen devices consume a large amount
of power, but in return can display large amounts of information or
display intricate screens. Simpler devices, such as a simple switch
used for light switches or power buttons, offer low cost and small
size, but can generally only receive very simple input from a user,
such as an on/off command.
SUMMARY
[0004] To better interact with humans, the next generation of
electronic devices can use triboelectric sensors to interact with a
human's sense of the touch. A triboelectric sensor may determine an
amount of force applied to the sensor by a user, such as with their
hand or fingers, and translate the applied force to an electrical
signal. Triboelectric-based sensors, which operate under the
principle of contact electrification to detect force or touch, use
a load connected to the current collector or other electrode. The
load can be provided by connecting a rigid resistive element to the
sensor. A rigid resistor does not allow the triboelectric sensor to
have a mechanically flexible form factor, or be manufactured in a
film-like configuration for mobile applications.
[0005] A thin film resistor can be used as a load to operate
triboelectric sensors. Alloys of chromium-silicon (Cr--Si),
nickel-chromium (Ni--Cr), and tantalum nitride (TaN) are the
typical materials that may be used for the fabrication of thin film
resistors for triboelectric sensors. Higher resistivity values can
be achieved with other materials. Higher resistivity materials
improve operation of the triboelectric sensor. A thin film resistor
of 100-200 MOhms or higher as a load can provide improved operation
of the triboelectric sensor. A size, or length, of the thin film
resistor can be adjusted to provide a desired resistance value for
a triboelectric sensor. For some configurations of material (e.g.,
NiCr) having low resistance values the length of the thin film
resistor may be a large distance. The length of the thin film
resistor can be decreased by using materials with higher resistance
values. The thin film resistor can be integrated with the
triboelectric sensor on a flexible substrate in a flexible sensor
package.
[0006] The thin film resistor can have a shape designed to obtain a
resistance value while using limited area in an integrated circuit.
For example, a serpentine shape can allow longer, and thus higher
resistance, thin film resistors for a triboelectric-based sensor.
The thin film resistor can be coupled to a triboelectric material
through an electrode. The electrode and the thin film resistor can
be in the same thin film layer of the integrated circuit.
Furthermore, the electrode and the thin film resistor can be made
of the same material, which can be a transparent conductive oxide.
The percentage of oxygen between the electrode and the thin film
resistor can be adjusted to obtain a higher resistance in the thin
film resistor, even when the thin film resistor and electrodes are
made from the same material.
[0007] An electronic device for receiving touch-based user input
can include a triboelectric sensor made with a triboelectric
material and a thin film layer coupled to the triboelectric
material and configured to provide a load to the triboelectric
material. The thin film material can include an electrode portion
coupled to the triboelectric material and a resistive portion
coupled to the electrode portion. The resistive portion can be
characterized by a higher resistivity than the electrode portion.
In some configurations of such an electronic device, the resistive
portion and the electrode portion can be made of a common material.
When a transparent device is made with the triboelectric sensor,
the common material can be a transparent conducting oxide, with a
portion of the transparent conducting oxide treated to increase the
resistance value.
[0008] One non-limiting example of an electronic device with a
triboelectric sensor can be a light switch for a room. A
conventional light switch must be wired to the lighting fixture
between the lighting fixture and an external power supply. In a
large room where a light is on opposite side of the room from the
wall switch, a large amount of wire is used to connect the switch
to the lighting fixture. The wire often has to pass through wall
space or ceiling space that is difficult to access and/or may be
damaged during the installation and require time and materials to
repair. An electronic device with a triboelectric sensor can be
used as a wall switch for a lighting fixture without wiring the
switch to the fixture. When a user applies force to the
triboelectric-based wall switch, a lighting fixture can be turned
on, turned off, set to a desired brightness, and/or set to a
desired color.
[0009] Although a wall switch is described as one application for
embodiments of the invention described herein, other applications
are possible. For example, an electronic device with a
triboelectric sensor can be incorporated into consumer electronic
devices, such as mobile devices, as power switches, as volume
controls, or as another input device. When the materials for the
triboelectric-based sensor are transparent, the triboelectric-based
sensor can be integrated into a display device. Furthermore,
although a lighting fixture is described as a receiver of remote
communications, the force sensitive device can communicate a touch
event to any device communicatively coupled to light bulbs or any
other processing unit such as an automation system, light
management system, personal computer, or a mobile device that is
able to interrogate another electronic device. The applications are
not limited to light switches, but can be used as a substitute or
supplement to any mechanical switching system. These switches may
not require wiring to the central unit and the installation is
simpler. For example, the mechanical switches in vehicles (e.g.,
engine start, doors, windows, seats, and the like) can be
controlled wirelessly according to embodiments of invention.
[0010] An electronic device can be manufactured, such as through an
exemplary method that includes forming a triboelectric-based sensor
on a substrate; forming an integrated circuit, such as a
communications device and/or read-out circuitry, on the substrate;
and/or coupling the IC to the triboelectric-based sensor through a
thin film resistor. The triboelectric-based sensor can be
manufactured with an electrode portion of a thin film layer
underneath the triboelectric material, that electrode portion may
be coupled to a resistive portion functioning as the thin film
resistor for the triboelectric sensor.
[0011] The triboelectric thin film layer can include at least one
of a perfluoronated copolymer, polyvinylidene fluoride (PVDF), a
copolymer of PVDF, polydimethylsiloxane (PDMS),
poly(methylmethacrylate) (PMMA), polytetrafluoroethylene (e.g.,
Teflon.RTM. (Chemours Co., U.S.A.)), poly-xylylene polymer (e.g.,
parylene polymers), polymer foam,
poly(methylmethacrylate)-co-poly(1H-1H-perfluorooctyl
methacrylate), a fluorinated polymer, an electronegative polymer,
or other polymers, or blends thereof. The triboelectric-based
sensor and other parts, or all of, the triboelectric-based sensor
may be flexible. For example, the sensor or apparatus can be formed
on at least one of polyethylene terephthalate (PET), polyethylene
naphthalate (PEN), polycarbonate (PC) or co-polymers thereof, PMMA,
polyimide, and/or another thermoplastic material or blends thereof.
In some embodiments, the substrate may also be transparent.
[0012] The triboelectric-based sensor can facilitate the processing
and transmission of user input received at the triboelectric-based
sensor. A processor, or other logic circuitry, can be configured
through hardware, software, and/or firmware to execute steps
including receiving, at a triboelectric-based sensor of a touch
device, an applied force; and converting, at the
triboelectric-based sensor of the touch device, the applied force
to an electrical signal that causes the electronic device to
perform certain other processing steps, such as transmission of the
user input to another electronic device, power on/off the
electronic device, increase or decrease a volume of the electronic
device, and/or the like.
[0013] The following includes definitions of various terms and
phrases used throughout this specification.
[0014] "Triboelectric sensor" or "triboelectric-based sensor" refer
to an electronic component configured to generate control signals
from user input to a triboelectric material. The triboelectric
sensor is an electronic component that may be integrated with or
coupled to an electronic device such as a cellular phone, mobile
phone, laptop computer, among others.
[0015] The terms "about" or "approximately" are defined as being
close to as understood by one of ordinary skill in the art. In one
non-limiting embodiment, the terms are defined to be within 10%,
preferably within 5%, more preferably within 1%, and most
preferably within 0.5%.
[0016] The term "substantially" and its variations are defined to
include ranges within 10%, within 5%, within 1%, or within
0.5%.
[0017] The term "effective," as that term is used in the
specification and/or claims, means adequate to accomplish a
desired, expected, or intended result.
[0018] The use of the words "a" or "an" when used in conjunction
with any of the terms "comprising," "including," "containing," or
"having" in the claims, or the specification, may mean "one," but
it is also consistent with the meaning of "one or more," "at least
one," and "one or more than one."
[0019] The words "comprising" (and any form of comprising, such as
"comprise" and "comprises"), "having" (and any form of having, such
as "have" and "has"), "including" (and any form of including, such
as "includes" and "include") or "containing" (and any form of
containing, such as "contains" and "contain") are inclusive or
open-ended and do not exclude additional, unrecited elements or
method steps.
[0020] The apparatus of the present invention can "comprise,"
"consist essentially of," or "consist of" particular ingredients,
components, compositions, etc. disclosed throughout the
specification. With respect to the transitional phase "consisting
essentially of," in one non-limiting aspect, a basic and novel
characteristic of the apparatus of the present invention are their
abilities to facilitate the processing and transmission of user
input.
[0021] The foregoing has outlined rather broadly certain features
and technical advantages of embodiments of the present invention in
order that the detailed description that follows may be better
understood. Additional features and advantages will be described
hereinafter that form the subject of the claims of the invention.
It should be appreciated by those having ordinary skill in the art
that the conception and specific embodiment disclosed may be
readily utilized as a basis for modifying or designing other
structures for carrying out the same or similar purposes. It should
also be realized by those having ordinary skill in the art that
such equivalent constructions do not depart from the spirit and
scope of the invention as set forth in the appended claims.
Additional features will be better understood from the following
description when considered in connection with the accompanying
figures. It is to be expressly understood, however, that each of
the figures is provided for the purpose of illustration and
description only and is not intended to limit the present
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] For a more complete understanding of the disclosed system
and methods, reference is now made to the following descriptions
taken in conjunction with the accompanying drawings.
[0023] FIG. 1 is a top-down view of a triboelectric-based sensor
with a thin film load resistor according to some embodiments of the
disclosure.
[0024] FIG. 2 is a flow chart illustrating a method of forming a
triboelectric-based sensor with a thin film load resistor according
to some embodiments of the disclosure.
[0025] FIG. 3 is a cross-sectional view of a triboelectric-based
sensor with a thin film load resistor according to some embodiments
of the disclosure.
[0026] FIG. 4 is a top-down view of a triboelectric-based sensor
with a thin film load resistor with a serpentine shape according to
some embodiments of the disclosure.
[0027] FIG. 5 is a flow chart illustrating a method of forming a
triboelectric-based sensor with a thin film load resistor using
patterned deposition according to some embodiments of the
disclosure.
[0028] FIG. 6 is a graph illustrating a sheet resistance of a
transparent conductive material as a function of oxygen partial
pressure in the material according to some embodiments of the
disclosure.
[0029] FIG. 7 is a graph illustrating an output of a
triboelectric-based sensor using PVDF-TrFE with a 200 MegaOhm thin
film load resistor according to some embodiments of the
disclosure.
[0030] FIG. 8 is a flow chart illustrating a method of forming a
triboelectric-based sensor with a thin film load resistor by
modifying a deposited thin film according to some embodiments of
the disclosure.
[0031] FIG. 9 is a cross-sectional view of a triboelectric-based
sensor with a thin film load resistor and a protection film
according to some embodiments of the disclosure.
[0032] FIG. 10 is a block diagram illustrating a method of
operation of a triboelectric-based sensor according to some
embodiments of the disclosure.
[0033] FIG. 11 is a block diagram illustrating an integrated
circuit for processing signals from a triboelectric-based touch
sensor according to some embodiments of the disclosure.
[0034] FIG. 12 is a flow chart illustrating an exemplary method for
using a triboelectric-based sensor for generating wireless control
signals according to some embodiments of the disclosure.
[0035] FIG. 13 is a block diagram illustrating an apparatus with an
array of triboelectric-based touch sensors according to some
embodiments of the disclosure.
[0036] FIG. 14 is an illustration of a room with a
triboelectric-based light switch according to some embodiments of
the disclosure.
[0037] FIG. 15 is an illustration of a room with a
triboelectric-based light switch with an array of
triboelectric-based force sensors according to some embodiments of
the disclosure.
DETAILED DESCRIPTION
[0038] FIG. 1 is a top-down view of a triboelectric-based sensor
with a thin film load resistor according to some embodiments of the
disclosure. A triboelectric material 110 may be deposited as a
triboelectric layer or second layer on a first thin film layer 120.
The thin film layer 120 may include a first electrode portion 122
in contact with the triboelectric material 110, a resistive portion
124, and a second electrode portion 126. An apparatus built around
the triboelectric-based sensor 100 may include a force sensor, an
integrated circuit (IC), and/or other components, such as a radio
frequency (RF) antenna. The triboelectric material 110 may include
PVDF or its copolymers (e.g., PVDF-trifluoroethylene (TrFE),
PVDF-TrFE chlorofluoroethylene (CFE), and PVDF-hexafluoropropylene
(HFP)), PDMS, PMMA, polytetrafluorethylene (e.g., Teflon.RTM.),
polymer foams,
poly(methylmethacrylate)-co-poly(1H-1H-perfluorooctyl
methacrylate), or other electronegative polymers. The thin film
layer 120 may be made from one or more of tantalum nitride, silicon
chromium alloys nickel chromium alloys, and/or transparent
conductive materials (e.g., indium tin oxide (ITO)). A method of
fabricating a triboelectric-based sensor with thin film resistor is
described with reference to FIG. 2.
[0039] FIG. 2 is a flow chart illustrating a method of forming a
triboelectric-based sensor with a thin film load resistor according
to some embodiments of the disclosure. A method 200 begins at block
202 with forming a thin film layer having an electrode portion and
a resistive portion. In some embodiments, the electrode portion and
the resistive portion can be made from a common material, such as a
transparent conductive material (e.g., ITO). Some techniques for
forming the thin film layer and its different portions are
described in more detail below with reference to FIG. 5 and FIG. 8.
Next, at block 204, a triboelectric layer may be formed on at least
part of the thin film layer formed at block 202. The triboelectric
layer may be coupled to the thin film layer. The coupling may be by
physical contact between the triboelectric material and the
electrode portion of the thin film layer. A cross-sectional view of
an example resulting structure fabricated according to the method
200 is shown in FIG. 3.
[0040] FIG. 3 is a cross-sectional view of a triboelectric-based
sensor with a thin film load resistor according to some embodiments
of the disclosure. A thin film layer 120 can be deposited on a
substrate 302. The substrate 302 can be one of PET, PEN, PC, PMMA,
polyimide, or other thermoplastic materials, or flexible or
inflexible substrate materials. Some layers may be present between
the substrate 302 and the thin film layer 120, such as precursor
layers and/or circuitry layers. The thin film layer 120 may include
the first electrode portion 122, the resistive portion 124, and the
second electrode portion 126. The triboelectric material 110 is
shown above the first electrode portion 122 and in contact with the
first electrode portion 122. Electrical contact with the
triboelectric material 110 can be made by external circuitry
through the second electrode 126, through the resistive portion
124, and the first electrode portion 122. A force signal
proportional to force applied to the triboelectric material 110 may
be measured from the triboelectric material 110 by such external
circuitry through the electrode portion 126.
[0041] The resistive portion 124 can be patterned into one of many
different shapes, which may be seen from a top-down view of the
structure. One example shape for the resistive portion 124 is a
serpentine pattern. The resistance provided by the resistive
portion 124 may be proportional to a length between the first
electrode portion 122 and the second electrode portion 126. The
serpentine pattern can provide a long length without consuming a
large amount of die area. FIG. 4 is a top-down view of a
triboelectric-based sensor with a thin film load resistor with a
serpentine shape according to some embodiments of the disclosure.
The resistive material 124 is shown in a serpentine pattern between
the first electrode portion 122 and the second electrode portion
126. Other example shapes for the resistive material 124 include a
straight line, a diagonal line, a chord, or other shape.
[0042] The thin film layer may be formed with different
characteristics, e.g., resistances, in the resistive portion and
the electrode portion. One example process for fabricating such a
device is described with reference to FIG. 5. FIG. 5 is a flow
chart illustrating a method of forming a triboelectric-based sensor
with a thin film load resistor using patterned deposition according
to some embodiments of the disclosure. A method 500 may begin at
block 502 with depositing a resistor portion of a first thin film
layer to form a first pattern. Some of the first pattern may
include serpentine shapes. Then, at block 504, an electrode portion
of the first thin film layer can be deposited to form a second
pattern. The second pattern can be aligned with the first pattern
such that the electrode portion contacts the resistor portion at
certain locations. Those locations may place the resistor portion
of the second pattern in contact on two ends with a first and
second electrode from the electrode portion. Then, at block 506, a
triboelectric material may be deposited as a second thin film layer
on the first thin film layer. The triboelectric material can have a
third pattern. The third pattern can be aligned such that the
triboelectric material may overlap or otherwise form electrical
contact with an electrode in the electrode portion of block
504.
[0043] The formation of the first pattern of block 502 and the
second pattern of block 504 can be performed by one or more
semiconductor fabrication techniques. For example, lift-off
patterning can be formed by depositing a photoresist layer,
patterning the photoresist layer with the first pattern, developing
the photoresist layer, depositing a material for the resistor
portion, and then lifting off the remaining photoresist layer.
Either positive-tone or negative-tone photoresist materials may be
used and the patterning adjusted accordingly to obtain the desired
first pattern. In some embodiments, another temporary layer can be
used in addition to the photoresist layer. As another example, a
resistive material for the resistor portion may be deposited, a
photoresist layer deposited on the resistive material, the
photoresist layer patterned with the first pattern, the first
pattern transferred from the photoresist layer to the resistive
material, and then the photoresist layer removed. As a further
example, the resistive and electrode portions may be printed as an
alternative fabrication process. Similar processing methods may be
used for the formation of the electrode portion of the second
pattern at block 504 and the triboelectric material at block
506.
[0044] The resistor portion and the electrode portion of the first
thin film layer may be the same or different materials. For
example, for a transparent device the resistor and electrode
portions may both be a transparent conductive material (e.g., ITO).
The deposition process for the transparent conductive material may
be altered to change a resistivity of the transparent conductive
material to be higher for the resistor portion and lower for the
electrode portion. Deposition processes can be adjusted to change
the resistivity by, for example, adding oxygen to the material
during deposition, changing energies during plasma deposition,
changing chemistry during vapor deposition, or the like. In some
embodiments, the resistor portion and electrode portion may be
different materials. One non-limiting example of a technique for
adjusting resistivity of a material to allow the same material to
be used for electrode and resistor portions is described with
reference to FIG. 6.
[0045] FIG. 6 is a graph illustrating a sheet resistance of a
transparent conductive material as a function of oxygen partial
pressure in the material according to some embodiments of the
disclosure. A line 602 shows a sheet resistance of ITO, a
transparent conductive material, as a function of oxygen partial
pressure during deposition. The sheet resistance is relatively low
for low oxygen partial pressure, but increases rapidly beyond a
threshold oxygen partial pressure in region 604. For some
materials, the sheet resistance may increase significantly beyond
approximately 3 to 4% oxygen partial pressure. In an embodiment of
the ITO material shown in FIG. 6, the resistor portion of the first
thin film layer of block 502 may be ITO deposited with oxygen
partial pressure above 4% and the electrode portion of the first
thin film layer of block 504 may be ITO deposited with oxygen
partial pressure below 4%. Higher oxygen partial pressure during
deposition of the material results in more oxygen incorporation
into the ITO film, which modifies the characteristics of the ITO
film such as by increasing resistance of the ITO film. A similar
technique of oxygen incorporation, or incorporation of other
elements or materials, into other conductive materials can be used
to modify other conductive materials to form a resistive portion in
a similar manner.
[0046] A triboelectric-based sensor similar to that illustrated in
FIG. 3 and FIG. 4 was tested to demonstrate operation of the
sensor. The sensor was manufactured according to a process similar
to that of FIG. 5 with ITO for resistor and electrode portions of
the sensor with properties similar to those illustrated in FIG. 6.
The output of the sensor is shown in FIG. 7. FIG. 7 is a graph
illustrating an output of a triboelectric-based sensor using
PVDF-TrFE with a 200 MegaOhm thin film load resistor according to
some embodiments of the disclosure. The sensor includes a
PVDF-based triboelectric material for the second thin film layer,
and ITO transparent conductive material for the first thin film
layer. The resistor portion is shaped in a serpentine manner to
obtain a 200 MegaOhm thin film resistor coupled to the
triboelectric material. An output of the sensor is shown in the
graph of FIG. 7. A repeated application and release of force to the
triboelectric material causes the output signal from the sensor,
read from an electrode of the electrode portion of the first thin
film layer, to increase and decrease. The peak-to-peak output
signal may be up to 10 Volts, which is easily detected with an
integrated circuit coupled to the triboelectric-based sensor. The
output signal can be adjusted by adjusting the resistance value of
the thin film resistor coupled to the triboelectric-based
sensor.
[0047] The manufacturing process described in FIG. 5 and tested
with the test sensor of FIG. 7 is only one process for
manufacturing a triboelectric-based sensor in accordance with
aspects of this disclosure. Another manufacturing process is
described in FIG. 8. Whereas FIG. 5 describes separate patterning
of two portions of the first thin film layer, a single deposition
step may be used to form the separate portions of the first thin
film layer. A portion of the deposited material may then be treated
after deposition to form resistive and electrode portions, either
by treating portions to increase conductivity or treating portions
to increase resistivity. FIG. 8 is a flow chart illustrating a
method of forming a triboelectric-based sensor with a thin film
load resistor by modifying a deposited thin film according to some
embodiments of the disclosure.
[0048] A method 800 may begin at block 802 with depositing a
material, such as a transparent conducting material (e.g., ITO)
thin film layer. The deposited film may have characteristics
desirable for the electrode portion of the first thin film layer. A
portion of the first thin film layer may be treated at block 804 to
increase a resistance of that portion above a resistance of the
original film deposited at block 802. For example, a photoresist
layer can be deposited on the ITO and patterned and developed
according to the first pattern to expose a portion of the ITO.
Then, the exposed portion of the ITO may be bombarded with oxygen
ions to increase the oxygen content of the ITO film, or otherwise
modify the structure of the ITO to increase resistivity. The
photoresist layer and other temporary layers may be removed. A
triboelectric material may then be deposited at block 806. The
deposited triboelectric material may make electrical contact over a
portion of the thin film layer not modified by the treatment of
block 804.
[0049] A protective layer may be used to protect the resistive
portion of the thin film layer from unintended modifications or
damage. FIG. 9 is a cross-sectional view of a triboelectric-based
sensor with a thin film load resistor and a protection film
according to some embodiments of the disclosure. The resistors may
be coated by an appropriate oxygen barrier material, such as to
protect from oxidization that may affect the resistivity of film.
The protection layer material may be the same material as the
active material of the touch sensor, e.g., PVDF-based materials, or
another suitable oxygen and moisture barrier material. An example
embodiment using a protective layer is illustrated as sensor 900. A
protective material 910 may be deposited and/or patterned over
resistive portion 124. The protective material 910 may overlap over
portions of the electrode portions 122 and 126 to seal the
resistive portion 124 from external conditions. The protective
material 910 may have a shape that matches the resistive portion
124, such as a serpentine shape. Alternatively, the protective
material 910 may have a shape that covers the resistive portion
124, such as a rectangular shape that spans the serpentine shape of
the resistive portion 124. In some embodiments, the protective
material 910 may be deposited simultaneously with triboelectric
material 110 during, for example block 204 of the manufacturing
process of FIG. 2.
[0050] Exemplary operation of a triboelectric-based sensor, such as
by the apparatus of FIG. 1, is described in more detail with
reference to FIG. 10. FIG. 10 is a block diagram illustrating a
method of operation of a triboelectric-based sensor according to
some embodiments of the disclosure. Dataflow for operation of a
triboelectric-based sensor may begin at block 1002 with an
integrated circuit receiving a force input signal from the
triboelectric-based force sensor. Then, at block 1004, the
integrated circuit may perform signal processing, which may include
signal conditioning, and/or other mathematical determinations or
logic decisions based on the received input from the force sensor
of block 1002. The processed sensor signal may be used internal to
an electronic device incorporating the force sensor. The processed
signal may be used to control operation of the electronic device,
such as by indicating user input to the device to change operating
conditions or power on/off the device. In some embodiments, the
processed signal may be transmitted to another information system
and used to affect operation of another information system or used
to generate a control command for affecting operation internal of
the electronic device. At block 1006, the integrated circuit may
communicate wirelessly with another device, such as by transmitting
a signal based, at least in part, on a signal received from a force
sensor at block 1002 and processed in block 1004.
[0051] A non-limiting example circuit for reading out the force
sensor is shown in FIG. 11. FIG. 11 is a block diagram illustrating
an integrated circuit for processing signals from a
triboelectric-based touch sensor according to some embodiments of
the disclosure. An IC 1120 may be coupled to a force sensor 1110 to
read out the output signal of the force sensor 1110. The force
sensor 1110 may be a triboelectric-based sensor, such as described
in embodiments shown in FIG. 1, FIG. 3, and FIG. 4, or other
embodiments. The IC 1120 may process the output signal received
from the force sensor 1110 to determine an amount of force applied
to the force sensor 1110. For example, the IC 1120 may use a
look-up table, an equation, an algorithm, or machine learning to
translate an output signal from the force sensor 1110 to a relative
or absolute force value. In some embodiments, the force value may
be used to determine whether a user has touched the force sensor
1110. In some touch sensor embodiments, the IC 1120 may determine
whether the force applied to the force sensor 1110 exceeds a
threshold amount that would indicate a deliberate touch on the
force sensor 1110. This binary determination may be used, for
example, to turn on or off devices. The IC 1120 may include
electrodes, interconnects, and/or antennas made from one or more of
aluminum, copper, silver, indium tin oxide (ITO), aluminum-doped
zinc oxide (AZO), poly(3,4-ethylenedioxythiophene) polystyrene
sulfonate (PEDOT:PSS), or any other conductive material, or blends
thereof.
[0052] The IC 1120 may transmit the determined applied force, or
other values derived from the applied force, through an antenna
1130. For example, a scaled analog value between 0 and 100 may be
generated by the IC 1120 based on the output signal of the force
sensor 1110, and that scaled analog value transmitted through the
antenna 1130. In another example, a binary value of true or false
may be generated by the IC 1120 based on the output signal of the
force sensor 1110 being higher or lower than a threshold value, and
that binary value transmitted through the antenna 1130. The IC 1120
may communicate using the antenna using any wireless communications
technique. In some embodiments, the IC 1120 may include
Bluetooth.RTM. (Bluetooth Special Interest Group, U.S.A.)
functionality and operate the antenna according to the
Bluetooth.RTM. standard. In some embodiments, the IC 1120 may
include WiFi functionality and operate the antenna in accordance
with the IEEE 802.11 standard. In some embodiments, the IC 1120 may
include frequency modulation (FM) or amplitude modulation (AM)
circuitry to transmit signals through the antenna.
[0053] One specific IC 1120 configured to provide some of the
above-described functionality is shown in FIG. 11. The IC 1120 may
include an input node for receiving signals from the sensor 1110,
such as when coupled to an electrode portion of the first thin film
layer. The received signal may be received by a sensor read-out
module 1112. The read-out may be provided to pre-processing module
1114, which may perform operations on and/or involving the read-out
from the sensor 1110. The processed signal may be provided to an RF
processing module 1116, which may perform operations to transmit
data to another device, such as by generating physical signals for
output to other circuitry in an electronic device, such as a
network interface for output of the signals to an RF antenna
1130.
[0054] In some embodiments, the IC 1120 may include a power module
1102. The power module 1102 may receive a supply voltage from a
power supply and distribute power to the modules 1112, 1114, and
1116. The power module 1102 may include circuitry such as power
converters, DC-to-DC converters, charge pumps, and the like to
convert the supply voltage into a steady-state DC power supply for
operating the modules 1112, 1114, and 1116. For example, the power
module 1102 may generate a 1.8 Volt DC power supply for operating
the modules 1112, 1114, and 1116.
[0055] The modules 1112, 1114, and/or 1116 may include circuitry
configured to perform the operations described herein. In some
embodiments, such as when the IC 1120 is a general-purpose
processor, the modules 1112, 1114, and/or 1116 may be software code
that when executed by a general-purpose processor cause the
processor to perform the operations described herein. In some
embodiments, the modules 1112, 1114, and/or 1116 may include
circuitry or other hardware configured to perform certain
functionality. In some embodiments, the circuitry or other hardware
may be configured using firmware. One example of a method for
implementation by the modules 1112, 1114, and/or 1116, in
cooperation with the sensor 1110, is described with reference to
FIG. 12.
[0056] FIG. 12 is a flow chart illustrating an exemplary method for
using a triboelectric-based sensor for generating wireless control
signals according to one embodiment of the disclosure. A method
1200 may begin at block 1202 with receiving, at a
triboelectric-based sensor, an applied force. At block 1204, the
applied force at the triboelectric-based sensor may be converted to
an electric signal. For example, a user's finger may apply a force
to a triboelectric layer, which generates charges in the
triboelectric layer as a result of the principle of contact
electrification. The user's applied force may correspond to an
input signal. For example, tapping the triboelectric material may
indicate turning on or off a device, such as a lighting device and
tapping the triboelectric material twice may indicate turning off
or on a device. As another example, tapping the triboelectric
material may indicate initiating or hanging up a telephone call or
other communications session.
[0057] Charges are generated in the triboelectric layer upon
contact with a material having an opposite electro affinity. For
example, charges are generated when a human finger touches the
triboelectric layer as a result of the principle of contact
electrification (e.g., triboelectrification). The power output of
the sensor may depend on the load (e.g., resistance) of the system.
The resistors may be formed from the resistor portions of the first
thin film layer. The signal generated by the triboelectric-based
force sensor may be conveyed to a thin film integrated circuit for
conditioning and pre-processing before being communicated via near
field radio frequency communication to a receiving device.
[0058] Referring back to FIG. 12, at block 1206, the electrical
signal from the triboelectric-based sensor may be applied to a
radio frequency (RF) communications device. The RF communications
device may include an integrated circuit, such as integrated
circuit 1120 of FIG. 11. The integrated circuit 1120 may include,
for example, a sensor read-out module 1112, configured to receive
the electrical signal from the triboelectric-based sensor at block
1206. The RF communications device may then perform steps to
prepare the output of the force sensor for transmission, and then
transmit a signal that corresponds to the output of the force
sensor. At block 1208, the electrical signal may be converted by
the RF communications device to a wireless signal. In one
embodiment, the conversion of block 1208 may be performed by
pre-processing module 1114 and/or RF processing module 1116 of FIG.
11. For example, the electrical signal may be processed and used to
generate wireless signals for near-field RF communications. At
block 1210, the wireless signal may be transmitted by the RF
communications device to a receiving device, such as through RF
antenna. In one embodiment, the transmission of block 1210 may be
performed by the RF processing module 1116 and/or the RF antenna.
The receiving device may be a lighting device, such as a lamp or
communication-enabled LED-based light bulb. The receiving device
may alternatively be a computing device, such as a mobile phone, a
tablet, a laptop computer, or a desktop computer.
[0059] Example embodiments described above include a single
triboelectric-based sensor, however, in some embodiments, multiple
sensors may be organized into an array FIG. 13 is a block diagram
illustrating an apparatus with an array of triboelectric-based
touch sensors according to one embodiment of the disclosure. An
electronic device 1300 may include an array 1310 of
triboelectric-based sensors. Each of the triboelectric-based
sensors 1310A-N may include a thin film sensor 1312A-N having a
triboelectric active layer and a thin film resistor 1314A-N. The
thin film resistors 1314A-N may be the resistor portions of the
first thin film layer illustrated as material 124 in FIG. 1, FIG.
3, and FIG. 4. Each of the sensors 1310A-N of the array 1310 may be
coupled to an integrated circuit (IC) 1320 for processing the
signals generated by the sensors 1310A-N. The IC 1320 may include a
read-out and decoder module 1322 configured to receive input
signals from each of the sensors 1310A-N and decode a resulting
output. For example, the module 1322 may be able to decode the
signals to determine which of the sensors 1310A-N were touched. In
another example, the module 1322 may be able to decode the signals
to determine an input value, such as where pressure applied to
different areas indicates different input values. The read-out
and/or decoded data may be passed to pre-processing module 1324 to
perform operations similar to the pre-processing module 1114 of
FIG. 11, and then to RF processing module 1126 to perform
operations similar to the RF processing module 1116 of FIG. 11.
[0060] In some embodiments, the thin film sensor array 1310 and/or
IC 1320 may be built on a flexible plastic substrate allowing the
device to take different form factors. For example, the device may
be fabricated on a flat substrate and, after proper encapsulation,
the device may be used as a remote light switch that connects with
a reader unit that is connected directly to a light bulb. A device
with multiple sensors may be used to control the light intensity by
touching different areas of the array of sensors, which are mapped
to the different intensities and may be decoded by the module 1322.
In one mapping, increasing the light intensity may be indicated by
a user as consecutive columns are touched. As another example, the
device may be fabricated on a transparent flexible substrate and
the device may have a transparent electrode portion, a transparent
resistive portion, and a transparent triboelectric material, such
that the device can be incorporated into a display device.
[0061] Thin film triboelectric sensors according to some
embodiments may have a triboelectric layer based on a
perfluoronated copolymer. The perfluoronated copolymer may be, for
example, poly(methyl methacrylate)-co-poly(1H-1H-perfluorooctyl
methacrylate). The perfluoronated copolymer may be manufactured by
known step polymer techniques. In one non-limiting example, the
copolymer can be polymerized using a free radical initiator in a
nonpolar inert solvent capable of dissolving the polymer precursors
(e.g., benzene). In some embodiments, the perfluoronated copolymer
may have a controlling perfluoro segment in proportion by weight of
more than approximately fifty percent. Particular embodiments of
synthesis for a triboelectric thin film are described below, but
other copolymers, such as those described above, may be
manufactured by different techniques.
[0062] In one embodiment,
poly(methylmethacrylate)-co-poly(1H-1H-perfluorooctyl methacrylate)
can be synthesized from methylmethacrylate (1) and
(1H-1H-perfluorooctyl methacrylate (2) to produce
poly(methylmethacrylate)-co-poly(1H-1H-perfluorooctyl methacrylate)
(3) as shown in the reaction scheme below:
##STR00001##
[0063] In one embodiment, the synthesis can include purification of
the starting materials. By way of example, benzene can be dried and
purified by refluxing benzene over sodium/potassium alloy in the
presence of benzophenone until the characteristic blue color of the
benzophenone radical anion was present and then distilled.
Azo-bisisobutyronitrile (AIBN) can be recrystallized from methanol
and dried in vacuum. Methylmethacrylate can freshly distilled under
a N.sub.2 atmosphere prior to use. 1H-1H-perfluorooctyl
methacrylate can be purified by passing through a basic alumina
column and dried over sodium sulfite (Na.sub.2SO.sub.4). Dry
benzene (e.g., 30 mL) was added to a reactor equipped with a
nitrogen inlet and reflux condenser in subdued light. The benzene
was degassed (e.g., nitrogen gas can be passed through the benzene
for about 1.5 hours), and methyl methacrylate (1) (e.g., 1.0 g (10
mmol)) and 1H-1H-perfluorooctyl methacrylate (2) (e.g., 1.0 g (2.1
mmol)) was added under agitation until dissolution of the reagents.
2,2'-Azobis-isobutyronitrile (AIBN, e.g., 20 mg) was added, and the
reaction mixture was allowed to react at 75 to 85 .degree. C. or
about 80 .degree. C. with agitation until the reaction was
considered complete (e.g., about 10 to 15 hours or about 12 hours).
The co-polymer was precipitated from the viscous solution by the
addition of a polar solvent (e.g., 250 mL of methanol). The
co-polymer was isolated using known solid/liquid techniques (e.g.,
filtration, centrifugation, and the like), and was further purified
by two subsequent precipitations from chloroform into methanol. The
purified copolymer was isolated and dried under vacuum. The
resulting polymer had a white color. The resultant copolymer can
have a molecular weight of between 5,000-50,000, or more
particularly 8,700, and a dispersity index (DPI) of 1.5-2.5, or
more particularly 2.01.
[0064] One example application for an electronic device with a
triboelectric sensor is wall switches for operating lighting
fixtures. FIG. 14 is an illustration of a room with a
triboelectric-based light switch according to one embodiment of the
disclosure. A room 1400 may include lighting fixtures 1402 and
1404. An electronic device, such as wall switch 1406, may include a
triboelectric sensor 1406A. When pressure is applied to the
triboelectric sensor 1406A, the sensor 1406A may generate an
electrical signal that is conveyed to an RF communications device.
An integrated circuit in the RF communications device may receive
the signal, process the signal, and generate an RF signal for
application to an RF antenna. The RF communications device may thus
generate and/or cause transmission of a control signal based on an
applied force to the sensor 1406A. The control signal may be
transmitted to the lighting fixtures 1402 and 1404 to turn on or
turn off the fixtures 1402 and 1404 or to dim the fixtures 1402 and
1404 to a level indicated by the applied force to the sensor 1406A.
Although wall lighting fixtures 1402 and 1404 are illustrated in
FIG. 14, the wall switch 1406 may control any device in the room,
including power outlets, stereo equipment, televisions, air
conditioners, heaters, mobile devices, home automation systems,
etc.
[0065] An array of triboelectric sensors may be used in a wall
switch for operating lighting fixtures as shown in FIG. 15. FIG. 15
is an illustration of a room with a triboelectric-based light
switch with an array of triboelectric-based force sensors according
to one embodiment of the disclosure. A room 1500 may include
lighting fixtures 1502 and 1504 and a wall switch 1506. The switch
1506 may include triboelectric sensors 1506A-I. The switch 1506 may
operate similar to the switch 1406 but transmit different signals
or a plurality of signals to a plurality of devices. For example,
one sensor 1506A may be used to control the lighting fixture 1502,
while a second sensor 1506B may be used to control the lighting
fixture 1504. In another example, the sensors 1506A-I may be used
to control an intensity of each fixture 1502-1504, such as when one
column of sensors 1506A-C varies the intensity of fixture 1502 and
another column of sensors 1506D-F varies the intensity of fixture
1504. In a further example, the sensors 1506A-I may be used to
control color of the fixtures 1502 and 1504, such as when one
column of sensors 1506A-C varies an intensity of emitted red light,
a second column of sensors 1506D-F varies an intensity of emitted
green light, and a third column of sensors 1506G-I varies an
intensity of emitted blue light from the lighting fixtures 1502 and
1504.
[0066] A triboelectric-based sensor may be improved according to
certain embodiments described herein and in accordance with the
principles and techniques described herein. The output voltage (or
power) generated by the triboelectric-based sensor depends, in
part, on the load (e.g., resistance) of the resistor coupled to the
sensor. Enhancements described herein may allow integration of a
thin film resistor made of transparent conducting oxide (TCO) with
a triboelectric-based touch/force sensor, in which the load (or
resistance value) can be adjusted by an amount of oxygen
incorporated into the TCO film, such as by changing an oxygen level
present during the deposition of the TCO film. Non-limiting
examples of transparent conducting oxides include tin-doped indium
oxide (ITO), aluminum-doped zinc oxide (AZO), gallium-doped zinc
oxide (GZO), tin dioxide (SnO.sub.2), and fluorine-dope tin oxide
(FTO).
[0067] If implemented in firmware and/or software, the functions
described above, such as with respect to the illustrations of FIG.
10, FIG. 11, FIG. 12, and FIG. 13, may be stored as one or more
instructions or code on a computer-readable medium. Examples
include non-transitory computer-readable media encoded with a data
structure and computer-readable media encoded with a computer
program. Computer-readable media includes physical computer storage
media. A storage medium may be any available medium that can be
accessed by a computer. By way of example, and not limitation, such
computer-readable media can comprise random access memory (RAM),
read-only memory (ROM), electrically erasable programmable
read-only memory (EEPROM), compact-disc read-only memory (CD-ROM)
or other optical disk storage, magnetic disk storage or other
magnetic storage devices, or any other medium that can be used to
store desired program code in the form of instructions or data
structures and that can be accessed by a computer. Disk and disc
includes compact discs (CD), laser discs, optical discs, digital
versatile discs (DVD), floppy disks, and Blu-ray discs. Generally,
disks reproduce data magnetically, and discs reproduce data
optically. Combinations of the above should also be included within
the scope of computer-readable media.
[0068] In addition to storage on computer readable medium,
instructions and/or data may be provided as signals on transmission
media included in a communication apparatus. For example, a
communication apparatus may include a transceiver having signals
indicative of instructions and data. The instructions and data are
configured to cause one or more processors to implement the
functions outlined in the claims.
[0069] The described methods are generally set forth in a logical
flow of steps. As such, the described order and labeled steps of
representative figures are indicative of aspects of the disclosed
method. Other steps and methods may be conceived that are
equivalent in function, logic, or effect to one or more steps, or
portions thereof, of the illustrated method. Additionally, the
format and symbols employed are provided to explain the logical
steps of the method and are understood not to limit the scope of
the method. Although various arrow types and line types may be
employed in the flow chart diagram, they are understood not to
limit the scope of the corresponding method. Indeed, some arrows or
other connectors may be used to indicate only the logical flow of
the method. For instance, an arrow may indicate a waiting or
monitoring period of unspecified duration between enumerated steps
of the depicted method. Additionally, the order in which a
particular method occurs may or may not strictly adhere to the
order of the corresponding steps shown.
[0070] Although the present disclosure and certain representative
advantages have been described in detail, it should be understood
that various changes, substitutions and alterations can be made
herein without departing from the spirit and scope of the
disclosure as defined by the appended claims. Moreover, the scope
of the present application is not intended to be limited to the
particular embodiments of the process, machine, manufacture,
composition of matter, means, methods and steps described in the
specification. As one of ordinary skill in the art will readily
appreciate from the present disclosure, processes, machines,
manufacture, compositions of matter, means, methods, or steps,
presently existing or later to be developed that perform
substantially the same function or achieve substantially the same
result as the corresponding embodiments described herein may be
utilized. Accordingly, the appended claims are intended to include
within their scope such processes, machines, manufacture,
compositions of matter, means, methods, or steps.
* * * * *